Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;

vector<ll> idx={1,0,-1,0};
vector<ll> idy={0,1,0,-1};

int main() {
  ll h,w;
  cin >> h >> w;
  vector<string> maze(h);
  for(ll i=0;i<h;i++) {
    cin >> maze[i];
  }
  vector<vector<ll>> ans(h,vector<ll>(w,-1));
  ans[0][0]=1;
  queue<pll> q;
  q.push(pll(0,0));
  while(q.size()) {
    auto p=q.front();
    ll y=p.first;
    ll x=p.second;
    q.pop();
    for(ll i=0;i<4;i++) {
      ll nx=x+idx[i];
      ll ny=y+idy[i];
      if(nx>-1&&nx<w&&ny>-1&&ny<h) {
        if(ans[ny][nx]<0&&maze[ny][nx]=='.') {
          q.push(pll(ny,nx));
          ans[ny][nx]=ans[y][x]+1;
        }
      }
    }
  }
  ll count=0;
  for(ll i=0;i<h;i++) {
    for(ll j=0;j<w;j++) {
      if(maze[i][j]=='#') {
        count++;
      }
    }
  }
  if(ans[h-1][w-1]<0) {
    cout << -1 << endl;
  }
  else {
    cout << h*w-count-ans[h-1][w-1] << endl;
  }
}